How often have you heard: “More high intensity exercise is good for you”? Don’t believe it, because it is a myth.

Yes, exercise is good for you and your heart. It also negatively impacts the immune system because of repeated injuries and internal inflammation.

This is precisely the reason why marathons are bad for your health. It puts your body through excruciating stress, not only on the day you run for the marathon, but also while training and can cause significant damage to the heart momentarily.

Extreme amounts of endurance exercise was said to be the cause of death of Mica True.

Reality Check for Marathon Runners

Micah True, an ultra-marathoner died of an unexpected heart attack during an exhaustive solo wilderness run in April 2012. His case gave way to suspicions – Does marathon training make runners immune to heart diseases or rather more susceptible to it?

National Health and Medical Research Council, Australia conducted a study on endurance athletes who took part in marathons and triathlons regularly. The study was conducted on athletes who trained for a minimum of 10-12 hours a week and had no pre-existing heart problems.

The data collected reported that most of these endurance athletes show damage caused to the right ventricle of the heart, though this kind of damage is not permanent and usually reverses itself naturally in healthy athletes. However, for those who are at risk to heart diseases, even this temporary damage could spell disaster.

Why exactly is that? High intensity exercise stretched over a long duration, like for example marathons and triathlons, can pose excess stress on the heart and disrupt the muscle fibers to cause micro-tears in the heart. The signs start to appear after the very first marathon you run. For some athletes this damage can be reversed, and the tears disappear within a week. However, for those who continue running marathons repeatedly year after year, the damage could be permanent because the muscle fibers aren’t able to repair themselves over and over again, and this can result in stiffness and scarring of the heart muscle.

American Cardiology Association agrees with this research and published a report in the editorial journal Heart to spread awareness about the fact that more and more high intensity exercise can do you more harm than good.

They warn,” A routine of moderate physical activity will add life to your years as well as years to your life. In contrast, running too far, too fast, and for too many years may speed one’s progress towards the finishing line of life”.

The researchers did a complete analysis on the athletes a couple of weeks before the race, an hour afterwards, and finally a week later. They conducted MRIs, Blood tests and Echocardiography to find evidence of any heart damage. Sadly, signs of damage were evident immediately.

Should You Hang Up Your Running Shoes?

According to the President of American Running Association, Dr. Charles Schulman, it is rather too early to say for sure how a healthy body reacts to the external stress marathon running poses. Experts agree with him – if you don’t have any serious pre-existing medical conditions and are at no risk to heart disease, you could probably still take part in marathons from time to time.

However, it is best to err on the side of caution. Don’t take part in more than one marathon a year and discontinue marathon running completely after you have done it a few times to make the shift to more heart-friendly workout routines in order to stay healthy. Excessive stress caused due to high intensity exercises is not good for anybody, healthy or not.

Also, it is best to keep high intensity exercises limited to no more than 50-60 minutes a day. Anymore than that and you could be inviting trouble you don’t want to deal with, or worse, even endangering your life in the long run.